1. Field of the Invention
The invention relates to wireless communications. More particularly, the invention relates to an apparatus for providing a multi-mode interface between a baseband integrated circuit and a radio frequency integrated circuit.
2. Description of the Related Art
Traditionally, a baseband integrated circuit (IC) may only be connected with a radio frequency (RF) IC through a fixed interface. As illustrated in FIG. 1A, RF circuitry 120 has an interface to transmit and receive single-ended voltage signals to and from baseband circuitry 110. The baseband circuitry 110 provides a corresponding interface to transmit a single-ended voltage signal 130 to the RF circuitry 120, and to receive a single-ended voltage signal 131 from the RF circuitry 120. Referring to FIG. 1B, RF circuitry 122 has an interface to transmit and receive differential voltage signals to and from baseband circuitry 112. To work with the RF circuitry 122, the baseband circuitry 112 provides a corresponding interface to transfer differential voltage signal pairs 132 and 133 with the RF circuitry 122. Turning now to FIG. 1C, baseband circuitry 114 provides an interface to transmit a pair of differential current signals 134 to RF circuitry 124, and to receive a pair of differential current signals 135 from the RF circuitry 124. Hence, the RF circuitry 124 must have a corresponding interface to receive and transmit differential current signals.
However, a conventional baseband IC with a fixed interface, which, as described above, will lack freedom in the choice of an appropriate RF IC. The conventional baseband IC also suffers from difficulty in replacing an existing RF IC with other types. Therefore, what is needed is a baseband IC, especially, a baseband receiver incorporating a multi-mode interface to flexibly connect a wide variety of types of RF circuitry, unencumbered by the limitations associated with the prior art.